DOI QR코드

DOI QR Code

전기비저항 모니터링을 이용한 저수지 제체 취수시설 취약성 해석

Analysis of a Weak Zone in Embankment Close to a Drainage using Resistivity Monitoring Data

  • 임성근 (한국농어촌공사 농어촌연구원)
  • 투고 : 2017.09.01
  • 심사 : 2018.01.31
  • 발행 : 2018.02.28

초록

저수지 제체에 대한 자연재해 피해를 예방하고 보수 및 보강대책을 수립하기 위해서 각종 계측기와 재해예방 전기비저항 모니터링 시스템을 설치하여 관리하고 있다. 대부분 30년 이상으로 노후화된 저수지는 농업용 관개에 따른 구조적인 취약성을 가지고 있다. 계측 및 모니터링 목적은 저수지의 안전성과 견고성을 확보하는데 있는데, 전기비저항탐사는 결함 부위, 침투수 이상대 및 제체 내 세굴현상 등과 같은 잠재적인 취약성 파악이 가능하다. 국내 한 저수지 제체 댐마루에 설치된 전기비저항 자동계측시스템을 통하여 매일 6시간 간격으로 저장된 연간 모니터링 자료를 이용하여, 제체 내 침투수 영향을 파악하였다. 연간 저수위 변화는 10m 정도인데, 영농기 취수에 따른 저수위 변화는 제체 내 물성변화를 야기한다. 모니터링 자료 해석 결과, 비저항 값은 연간 저수위 및 계절영향 이외에 대체로 안정적이었다. 또한, 제체 내 취수시설 주변의 취약성 고찰을 위해서 단순화된 모델을 구성하여 모델링을 수행하였다. 그 결과 전기비저항 모델 반응 계산을 통한 복통구조물 주변 침투수 구간의 탐지가 가능함을 확인하였다.

For the purpose of maintenance and prevention of earth fill dams against damage from natural hazards, automatic monitoring through various measuring instruments and resistivity survey has been carried out. Reservoirs and embankments have the structural vulnerability on the agricultural usages since most of them were built more than thirty years ago. The main aim to use monitoring method is to verify the safety and integrity of the dam. Resistivity survey can detect potential weaknesses, such as defective zones, anomalous seepages or internal erosion processes. Permanent resistivity monitoring systems were installed at a reservoir, which daily measurements have been taken every 6 hour. Using monitoring data for one year, anomalous seepage and structural defects were clarified for dam safety. Annual water level fluctuations are around 10 m. During their operation, reservoir dams are subject to a never-ending hydraulic load from the reservoir, which over the years may cause changes in the properties of the inner parts of the dam construction. Detailed analysis of the monitoring results was performed and showed that resistivities at most locations have been very stable over the full monitoring period excluding the effects of water fluctuation and seasons. To investigate the detectability of weak zone using the DC resistivity monitoring, numerical modeling with a simplified model for the drainage at a reservoir dam was also performed. The results showed that the seepage zone near drainage in a reservoir dam could be detected by resistivity response change.

키워드

참고문헌

  1. Cockett, R., Kang, S., Heagy, L. J., Pidlisecky, A., and Oldenburg, D. W., 2015, SimPEG: An open source framework for simulation and gradient based parameter estimation in geophysical applications, Comput. Geosci., 85, 142-154. https://doi.org/10.1016/j.cageo.2015.09.015
  2. Jang, B. S., Im, E. S., and Oh, B. H., 2008, Methodologies for survey and retrofit of small dams pierced by diversion tunnel, J. Korea Inst. for Structural Maintenance and Inspection, 12, 75-82 (in Korean with English abstract).
  3. Korea rural community cooperation, 2016, Statistical yearbook of agricultural production infrastructure maintenance, 2015 Ed. (in Korean).
  4. Park, S. G., Kim, J.-H., and Seo, G. W., 2005, Application of electrical resistivity monitoring technique to maintenance of embankments, Geophys. and Geophys. Explor., 8, 177-183 (in Korean with English abstract).
  5. Sjoahl, P., Dahlin, T., and Johansson, S., 2004, Resistivity monitoring for internal erosion detection at Halby embankment dam, Procs. Int. Conf. on Environ. Eng. Geoph., Wuhan, China, 6-9.
  6. Song, S. H., Song, Y. H., and Kwon, B. D., 2005, Application of hydrogeological and geophysical methods to delineate leakage pathways in an earth fill dam, Explor. Geophys., 36, 92-96. https://doi.org/10.1071/EG05092
  7. Yi, M.-J., Kim, J.-H., Song, Y., and chung, S.-H., 2000, Dam seepage using two-and three-dimensional resistivity surveys, Proceeding of the 2nd Special Symposium of KSEG, 41-53 (in Korean with English abstract).